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Sourcecode: freebsd-utils version File versions

authpf.c

/*    $OpenBSD: authpf.c,v 1.104 2007/02/24 17:35:08 beck Exp $   */

/*
 * Copyright (C) 1998 - 2007 Bob Beck (beck@openbsd.org).
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/contrib/pf/authpf/authpf.c,v 1.8.6.1 2008/11/25 02:59:29 kensmith Exp $");

#include <sys/param.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>

#include <net/if.h>
#include <net/pfvar.h>
#include <arpa/inet.h>

#include <err.h>
#include <errno.h>
#ifdef __FreeBSD__
#include <inttypes.h>
#endif
#include <login_cap.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include "pathnames.h"

static int  read_config(FILE *);
static void print_message(char *);
static int  allowed_luser(char *);
static int  check_luser(char *, char *);
static int  remove_stale_rulesets(void);
static int  change_filter(int, const char *, const char *);
static int  change_table(int, const char *);
static void authpf_kill_states(void);

int   dev;              /* pf device */
char  anchorname[PF_ANCHOR_NAME_SIZE] = "authpf";
char  rulesetname[MAXPATHLEN - PF_ANCHOR_NAME_SIZE - 2];
char  tablename[PF_TABLE_NAME_SIZE] = "authpf_users";

FILE  *pidfp;
char   luser[MAXLOGNAME];     /* username */
char   ipsrc[256];            /* ip as a string */
char   pidfile[MAXPATHLEN];   /* we save pid in this file. */

struct timeval    Tstart, Tend;     /* start and end times of session */

volatile sig_atomic_t   want_death;
static void       need_death(int signo);
#ifdef __FreeBSD__
static __dead2 void     do_death(int);
#else
static __dead void      do_death(int);
#endif

/*
 * User shell for authenticating gateways. Sole purpose is to allow
 * a user to ssh to a gateway, and have the gateway modify packet
 * filters to allow access, then remove access when the user finishes
 * up. Meant to be used only from ssh(1) connections.
 */
int
main(int argc, char *argv[])
{
      int          lockcnt = 0, n, pidfd;
      FILE        *config;
      struct in6_addr    ina;
      struct passwd     *pw;
      char        *cp;
      gid_t        gid;
      uid_t        uid;
      char        *shell;
      login_cap_t *lc;

      config = fopen(PATH_CONFFILE, "r");
      if (config == NULL) {
            syslog(LOG_ERR, "can not open %s (%m)", PATH_CONFFILE);
            exit(1);
      }

      if ((cp = getenv("SSH_TTY")) == NULL) {
            syslog(LOG_ERR, "non-interactive session connection for authpf");
            exit(1);
      }

      if ((cp = getenv("SSH_CLIENT")) == NULL) {
            syslog(LOG_ERR, "cannot determine connection source");
            exit(1);
      }

      if (strlcpy(ipsrc, cp, sizeof(ipsrc)) >= sizeof(ipsrc)) {
            syslog(LOG_ERR, "SSH_CLIENT variable too long");
            exit(1);
      }
      cp = strchr(ipsrc, ' ');
      if (!cp) {
            syslog(LOG_ERR, "corrupt SSH_CLIENT variable %s", ipsrc);
            exit(1);
      }
      *cp = '\0';
      if (inet_pton(AF_INET, ipsrc, &ina) != 1 &&
          inet_pton(AF_INET6, ipsrc, &ina) != 1) {
            syslog(LOG_ERR,
                "cannot determine IP from SSH_CLIENT %s", ipsrc);
            exit(1);
      }
      /* open the pf device */
      dev = open(PATH_DEVFILE, O_RDWR);
      if (dev == -1) {
            syslog(LOG_ERR, "cannot open packet filter device (%m)");
            goto die;
      }

      uid = getuid();
      pw = getpwuid(uid);
      if (pw == NULL) {
            syslog(LOG_ERR, "cannot find user for uid %u", uid);
            goto die;
      }

      if ((lc = login_getclass(pw->pw_class)) != NULL)
            shell = (char *)login_getcapstr(lc, "shell", pw->pw_shell,
                pw->pw_shell);
      else
            shell = pw->pw_shell;

      login_close(lc);

      if (strcmp(shell, PATH_AUTHPF_SHELL)) {
            syslog(LOG_ERR, "wrong shell for user %s, uid %u",
                pw->pw_name, pw->pw_uid);
            if (shell != pw->pw_shell)
                  free(shell);
            goto die;
      }

      if (shell != pw->pw_shell)
            free(shell);

      /*
       * Paranoia, but this data _does_ come from outside authpf, and
       * truncation would be bad.
       */
      if (strlcpy(luser, pw->pw_name, sizeof(luser)) >= sizeof(luser)) {
            syslog(LOG_ERR, "username too long: %s", pw->pw_name);
            goto die;
      }

      if ((n = snprintf(rulesetname, sizeof(rulesetname), "%s(%ld)",
          luser, (long)getpid())) < 0 || (u_int)n >= sizeof(rulesetname)) {
            syslog(LOG_INFO, "%s(%ld) too large, ruleset name will be %ld",
                luser, (long)getpid(), (long)getpid());
            if ((n = snprintf(rulesetname, sizeof(rulesetname), "%ld",
                (long)getpid())) < 0 || (u_int)n >= sizeof(rulesetname)) {
                  syslog(LOG_ERR, "pid too large for ruleset name");
                  goto die;
            }
      }


      /* Make our entry in /var/authpf as /var/authpf/ipaddr */
      n = snprintf(pidfile, sizeof(pidfile), "%s/%s", PATH_PIDFILE, ipsrc);
      if (n < 0 || (u_int)n >= sizeof(pidfile)) {
            syslog(LOG_ERR, "path to pidfile too long");
            goto die;
      }

      /*
       * If someone else is already using this ip, then this person
       * wants to switch users - so kill the old process and exit
       * as well.
       *
       * Note, we could print a message and tell them to log out, but the
       * usual case of this is that someone has left themselves logged in,
       * with the authenticated connection iconized and someone else walks
       * up to use and automatically logs in before using. If this just
       * gets rid of the old one silently, the new user never knows they
       * could have used someone else's old authentication. If we
       * tell them to log out before switching users it is an invitation
       * for abuse.
       */

      do {
            int   save_errno, otherpid = -1;
            char  otherluser[MAXLOGNAME];

            if ((pidfd = open(pidfile, O_RDWR|O_CREAT, 0644)) == -1 ||
                (pidfp = fdopen(pidfd, "r+")) == NULL) {
                  if (pidfd != -1)
                        close(pidfd);
                  syslog(LOG_ERR, "cannot open or create %s: %s", pidfile,
                      strerror(errno));
                  goto die;
            }

            if (flock(fileno(pidfp), LOCK_EX|LOCK_NB) == 0)
                  break;
            save_errno = errno;

            /* Mark our pid, and username to our file. */

            rewind(pidfp);
            /* 31 == MAXLOGNAME - 1 */
            if (fscanf(pidfp, "%d\n%31s\n", &otherpid, otherluser) != 2)
                  otherpid = -1;
            syslog(LOG_DEBUG, "tried to lock %s, in use by pid %d: %s",
                pidfile, otherpid, strerror(save_errno));

            if (otherpid > 0) {
                  syslog(LOG_INFO,
                      "killing prior auth (pid %d) of %s by user %s",
                      otherpid, ipsrc, otherluser);
                  if (kill((pid_t) otherpid, SIGTERM) == -1) {
                        syslog(LOG_INFO,
                            "could not kill process %d: (%m)",
                            otherpid);
                  }
            }

            /*
             * we try to kill the previous process and acquire the lock
             * for 10 seconds, trying once a second. if we can't after
             * 10 attempts we log an error and give up
             */
            if (++lockcnt > 10) {
                  syslog(LOG_ERR, "cannot kill previous authpf (pid %d)",
                      otherpid);
                  fclose(pidfp);
                  pidfp = NULL;
                  goto dogdeath;
            }
            sleep(1);

            /* re-open, and try again. The previous authpf process
             * we killed above should unlink the file and release
             * it's lock, giving us a chance to get it now
             */
            fclose(pidfp);
            pidfp = NULL;
      } while (1);
      
      /* whack the group list */
      gid = getegid();
      if (setgroups(1, &gid) == -1) {
            syslog(LOG_INFO, "setgroups: %s", strerror(errno));
            do_death(0);
      }

      /* revoke privs */
      uid = getuid();
      if (setresuid(uid, uid, uid) == -1) {
            syslog(LOG_INFO, "setresuid: %s", strerror(errno));
            do_death(0);
      }
      openlog("authpf", LOG_PID | LOG_NDELAY, LOG_DAEMON);

      if (!check_luser(PATH_BAN_DIR, luser) || !allowed_luser(luser)) {
            syslog(LOG_INFO, "user %s prohibited", luser);
            do_death(0);
      }

      if (read_config(config)) {
            syslog(LOG_ERR, "invalid config file %s", PATH_CONFFILE);
            do_death(0);
      }

      if (remove_stale_rulesets()) {
            syslog(LOG_INFO, "error removing stale rulesets");
            do_death(0);
      }

      /* We appear to be making headway, so actually mark our pid */
      rewind(pidfp);
      fprintf(pidfp, "%ld\n%s\n", (long)getpid(), luser);
      fflush(pidfp);
      (void) ftruncate(fileno(pidfp), ftello(pidfp));

      if (change_filter(1, luser, ipsrc) == -1) {
            printf("Unable to modify filters\r\n");
            do_death(0);
      }
      if (change_table(1, ipsrc) == -1) {
            printf("Unable to modify table\r\n");
            change_filter(0, luser, ipsrc);
            do_death(0);
      }

      signal(SIGTERM, need_death);
      signal(SIGINT, need_death);
      signal(SIGALRM, need_death);
      signal(SIGPIPE, need_death);
      signal(SIGHUP, need_death);
      signal(SIGQUIT, need_death);
      signal(SIGTSTP, need_death);
      while (1) {
            printf("\r\nHello %s. ", luser);
            printf("You are authenticated from host \"%s\"\r\n", ipsrc);
            setproctitle("%s@%s", luser, ipsrc);
            print_message(PATH_MESSAGE);
            while (1) {
                  sleep(10);
                  if (want_death)
                        do_death(1);
            }
      }

      /* NOTREACHED */
dogdeath:
      printf("\r\n\r\nSorry, this service is currently unavailable due to ");
      printf("technical difficulties\r\n\r\n");
      print_message(PATH_PROBLEM);
      printf("\r\nYour authentication process (pid %ld) was unable to run\n",
          (long)getpid());
      sleep(180); /* them lusers read reaaaaal slow */
die:
      do_death(0);

      /* NOTREACHED */
}

/*
 * reads config file in PATH_CONFFILE to set optional behaviours up
 */
static int
read_config(FILE *f)
{
      char  buf[1024];
      int   i = 0;

      do {
            char  **ap;
            char   *pair[4], *cp, *tp;
            int     len;

            if (fgets(buf, sizeof(buf), f) == NULL) {
                  fclose(f);
                  return (0);
            }
            i++;
            len = strlen(buf);
            if (buf[len - 1] != '\n' && !feof(f)) {
                  syslog(LOG_ERR, "line %d too long in %s", i,
                      PATH_CONFFILE);
                  return (1);
            }
            buf[len - 1] = '\0';

            for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
                  ; /* nothing */

            if (!*cp || *cp == '#' || *cp == '\n')
                  continue;

            for (ap = pair; ap < &pair[3] &&
                (*ap = strsep(&cp, "=")) != NULL; ) {
                  if (**ap != '\0')
                        ap++;
            }
            if (ap != &pair[2])
                  goto parse_error;

            tp = pair[1] + strlen(pair[1]);
            while ((*tp == ' ' || *tp == '\t') && tp >= pair[1])
                  *tp-- = '\0';

            if (strcasecmp(pair[0], "anchor") == 0) {
                  if (!pair[1][0] || strlcpy(anchorname, pair[1],
                      sizeof(anchorname)) >= sizeof(anchorname))
                        goto parse_error;
            }
            if (strcasecmp(pair[0], "table") == 0) {
                  if (!pair[1][0] || strlcpy(tablename, pair[1],
                      sizeof(tablename)) >= sizeof(tablename))
                        goto parse_error;
            }
      } while (!feof(f) && !ferror(f));
      fclose(f);
      return (0);

parse_error:
      fclose(f);
      syslog(LOG_ERR, "parse error, line %d of %s", i, PATH_CONFFILE);
      return (1);
}


/*
 * splatter a file to stdout - max line length of 1024,
 * used for spitting message files at users to tell them
 * they've been bad or we're unavailable.
 */
static void
print_message(char *filename)
{
      char   buf[1024];
      FILE  *f;

      if ((f = fopen(filename, "r")) == NULL)
            return; /* fail silently, we don't care if it isn't there */

      do {
            if (fgets(buf, sizeof(buf), f) == NULL) {
                  fflush(stdout);
                  fclose(f);
                  return;
            }
      } while (fputs(buf, stdout) != EOF && !feof(f));
      fflush(stdout);
      fclose(f);
}

/*
 * allowed_luser checks to see if user "luser" is allowed to
 * use this gateway by virtue of being listed in an allowed
 * users file, namely /etc/authpf/authpf.allow .
 *
 * If /etc/authpf/authpf.allow does not exist, then we assume that
 * all users who are allowed in by sshd(8) are permitted to
 * use this gateway. If /etc/authpf/authpf.allow does exist, then a
 * user must be listed if the connection is to continue, else
 * the session terminates in the same manner as being banned.
 */
static int
allowed_luser(char *luser)
{
      char  *buf, *lbuf;
      int    matched;
      size_t       len;
      FILE  *f;

      if ((f = fopen(PATH_ALLOWFILE, "r")) == NULL) {
            if (errno == ENOENT) {
                  /*
                   * allowfile doesn't exist, thus this gateway
                   * isn't restricted to certain users...
                   */
                  return (1);
            }

            /*
             * luser may in fact be allowed, but we can't open
             * the file even though it's there. probably a config
             * problem.
             */
            syslog(LOG_ERR, "cannot open allowed users file %s (%s)",
                PATH_ALLOWFILE, strerror(errno));
            return (0);
      } else {
            /*
             * /etc/authpf/authpf.allow exists, thus we do a linear
             * search to see if they are allowed.
             * also, if username "*" exists, then this is a
             * "public" gateway, such as it is, so let
             * everyone use it.
             */
            lbuf = NULL;
            while ((buf = fgetln(f, &len))) {
                  if (buf[len - 1] == '\n')
                        buf[len - 1] = '\0';
                  else {
                        if ((lbuf = (char *)malloc(len + 1)) == NULL)
                              err(1, NULL);
                        memcpy(lbuf, buf, len);
                        lbuf[len] = '\0';
                        buf = lbuf;
                  }

                  matched = strcmp(luser, buf) == 0 || strcmp("*", buf) == 0;

                  if (lbuf != NULL) {
                        free(lbuf);
                        lbuf = NULL;
                  }

                  if (matched)
                        return (1); /* matched an allowed username */
            }
            syslog(LOG_INFO, "denied access to %s: not listed in %s",
                luser, PATH_ALLOWFILE);

            /* reuse buf */
            buf = "\n\nSorry, you are not allowed to use this facility!\n";
            fputs(buf, stdout);
      }
      fflush(stdout);
      return (0);
}

/*
 * check_luser checks to see if user "luser" has been banned
 * from using us by virtue of having an file of the same name
 * in the "luserdir" directory.
 *
 * If the user has been banned, we copy the contents of the file
 * to the user's screen. (useful for telling the user what to
 * do to get un-banned, or just to tell them they aren't
 * going to be un-banned.)
 */
static int
check_luser(char *luserdir, char *luser)
{
      FILE  *f;
      int    n;
      char   tmp[MAXPATHLEN];

      n = snprintf(tmp, sizeof(tmp), "%s/%s", luserdir, luser);
      if (n < 0 || (u_int)n >= sizeof(tmp)) {
            syslog(LOG_ERR, "provided banned directory line too long (%s)",
                luserdir);
            return (0);
      }
      if ((f = fopen(tmp, "r")) == NULL) {
            if (errno == ENOENT) {
                  /*
                   * file or dir doesn't exist, so therefore
                   * this luser isn't banned..  all is well
                   */
                  return (1);
            } else {
                  /*
                   * luser may in fact be banned, but we can't open the
                   * file even though it's there. probably a config
                   * problem.
                   */
                  syslog(LOG_ERR, "cannot open banned file %s (%s)",
                      tmp, strerror(errno));
                  return (0);
            }
      } else {
            /*
             * luser is banned - spit the file at them to
             * tell what they can do and where they can go.
             */
            syslog(LOG_INFO, "denied access to %s: %s exists",
                luser, tmp);

            /* reuse tmp */
            strlcpy(tmp, "\n\n-**- Sorry, you have been banned! -**-\n\n",
                sizeof(tmp));
            while (fputs(tmp, stdout) != EOF && !feof(f)) {
                  if (fgets(tmp, sizeof(tmp), f) == NULL) {
                        fflush(stdout);
                        fclose(f);
                        return (0);
                  }
            }
            fclose(f);
      }
      fflush(stdout);
      return (0);
}

/*
 * Search for rulesets left by other authpf processes (either because they
 * died ungracefully or were terminated) and remove them.
 */
static int
remove_stale_rulesets(void)
{
      struct pfioc_ruleset     prs;
      u_int32_t          nr, mnr;

      memset(&prs, 0, sizeof(prs));
      strlcpy(prs.path, anchorname, sizeof(prs.path));
      if (ioctl(dev, DIOCGETRULESETS, &prs)) {
            if (errno == EINVAL)
                  return (0);
            else
                  return (1);
      }

      mnr = prs.nr;
      nr = 0;
      while (nr < mnr) {
            char  *s, *t;
            pid_t  pid;

            prs.nr = nr;
            if (ioctl(dev, DIOCGETRULESET, &prs))
                  return (1);
            errno = 0;
            if ((t = strchr(prs.name, '(')) == NULL)
                  t = prs.name;
            else
                  t++;
            pid = strtoul(t, &s, 10);
            if (!prs.name[0] || errno ||
                (*s && (t == prs.name || *s != ')')))
                  return (1);
            if (kill(pid, 0) && errno != EPERM) {
                  int               i;
                  struct pfioc_trans_e    t_e[PF_RULESET_MAX+1];
                  struct pfioc_trans      t;

                  bzero(&t, sizeof(t));
                  bzero(t_e, sizeof(t_e));
                  t.size = PF_RULESET_MAX+1;
                  t.esize = sizeof(t_e[0]);
                  t.array = t_e;
                  for (i = 0; i < PF_RULESET_MAX+1; ++i) {
                        t_e[i].rs_num = i;
                        snprintf(t_e[i].anchor, sizeof(t_e[i].anchor),
                            "%s/%s", anchorname, prs.name);
                  }
                  t_e[PF_RULESET_MAX].rs_num = PF_RULESET_TABLE;
                  if ((ioctl(dev, DIOCXBEGIN, &t) ||
                      ioctl(dev, DIOCXCOMMIT, &t)) &&
                      errno != EINVAL)
                        return (1);
                  mnr--;
            } else
                  nr++;
      }
      return (0);
}

/*
 * Add/remove filter entries for user "luser" from ip "ipsrc"
 */
static int
change_filter(int add, const char *luser, const char *ipsrc)
{
      char  *pargv[13] = {
            "pfctl", "-p", "/dev/pf", "-q", "-a", "anchor/ruleset",
            "-D", "user_ip=X", "-D", "user_id=X", "-f",
            "file", NULL
      };
      char  *fdpath = NULL, *userstr = NULL, *ipstr = NULL;
      char  *rsn = NULL, *fn = NULL;
      pid_t pid;
      gid_t   gid;
      int   s;

      if (luser == NULL || !luser[0] || ipsrc == NULL || !ipsrc[0]) {
            syslog(LOG_ERR, "invalid luser/ipsrc");
            goto error;
      }

      if (asprintf(&rsn, "%s/%s", anchorname, rulesetname) == -1)
            goto no_mem;
      if (asprintf(&fdpath, "/dev/fd/%d", dev) == -1)
            goto no_mem;
      if (asprintf(&ipstr, "user_ip=%s", ipsrc) == -1)
            goto no_mem;
      if (asprintf(&userstr, "user_id=%s", luser) == -1)
            goto no_mem;

      if (add) {
            struct stat sb;

            if (asprintf(&fn, "%s/%s/authpf.rules", PATH_USER_DIR, luser)
                == -1)
                  goto no_mem;
            if (stat(fn, &sb) == -1) {
                  free(fn);
                  if ((fn = strdup(PATH_PFRULES)) == NULL)
                        goto no_mem;
            }
      }
      pargv[2] = fdpath;
      pargv[5] = rsn;
      pargv[7] = userstr;
      pargv[9] = ipstr;
      if (!add)
            pargv[11] = "/dev/null";
      else
            pargv[11] = fn;

      switch (pid = fork()) {
      case -1:
            syslog(LOG_ERR, "fork failed");
            goto error;
      case 0:
            /* revoke group privs before exec */
            gid = getgid();
            if (setregid(gid, gid) == -1) {
                  err(1, "setregid");
            }
            execvp(PATH_PFCTL, pargv);
            warn("exec of %s failed", PATH_PFCTL);
            _exit(1);
      }

      /* parent */
      waitpid(pid, &s, 0);
      if (s != 0) {
            syslog(LOG_ERR, "pfctl exited abnormally");
            goto error;
      }

      if (add) {
            gettimeofday(&Tstart, NULL);
            syslog(LOG_INFO, "allowing %s, user %s", ipsrc, luser);
      } else {
            gettimeofday(&Tend, NULL);
#ifdef __FreeBSD__
            syslog(LOG_INFO, "removed %s, user %s - duration %jd seconds",
                ipsrc, luser, (intmax_t)(Tend.tv_sec - Tstart.tv_sec));
#else
            syslog(LOG_INFO, "removed %s, user %s - duration %ld seconds",
                ipsrc, luser, Tend.tv_sec - Tstart.tv_sec);
#endif
      }
      return (0);
no_mem:
      syslog(LOG_ERR, "malloc failed");
error:
      free(fdpath);
      free(rsn);
      free(userstr);
      free(ipstr);
      free(fn);
      return (-1);
}

/*
 * Add/remove this IP from the "authpf_users" table.
 */
static int
change_table(int add, const char *ipsrc)
{
      struct pfioc_table      io;
      struct pfr_addr         addr;

      bzero(&io, sizeof(io));
      strlcpy(io.pfrio_table.pfrt_name, tablename,
          sizeof(io.pfrio_table.pfrt_name));
      io.pfrio_buffer = &addr;
      io.pfrio_esize = sizeof(addr);
      io.pfrio_size = 1;

      bzero(&addr, sizeof(addr));
      if (ipsrc == NULL || !ipsrc[0])
            return (-1);
      if (inet_pton(AF_INET, ipsrc, &addr.pfra_ip4addr) == 1) {
            addr.pfra_af = AF_INET;
            addr.pfra_net = 32;
      } else if (inet_pton(AF_INET6, ipsrc, &addr.pfra_ip6addr) == 1) {
            addr.pfra_af = AF_INET6;
            addr.pfra_net = 128;
      } else {
            syslog(LOG_ERR, "invalid ipsrc");
            return (-1);
      }

      if (ioctl(dev, add ? DIOCRADDADDRS : DIOCRDELADDRS, &io) &&
          errno != ESRCH) {
            syslog(LOG_ERR, "cannot %s %s from table %s: %s",
                add ? "add" : "remove", ipsrc, tablename,
                strerror(errno));
            return (-1);
      }
      return (0);
}

/*
 * This is to kill off states that would otherwise be left behind stateful
 * rules. This means we don't need to allow in more traffic than we really
 * want to, since we don't have to worry about any luser sessions lasting
 * longer than their ssh session. This function is based on
 * pfctl_kill_states from pfctl.
 */
static void
authpf_kill_states(void)
{
      struct pfioc_state_kill psk;
      struct pf_addr target;

      memset(&psk, 0, sizeof(psk));
      memset(&target, 0, sizeof(target));

      if (inet_pton(AF_INET, ipsrc, &target.v4) == 1)
            psk.psk_af = AF_INET;
      else if (inet_pton(AF_INET6, ipsrc, &target.v6) == 1)
            psk.psk_af = AF_INET6;
      else {
            syslog(LOG_ERR, "inet_pton(%s) failed", ipsrc);
            return;
      }

      /* Kill all states from ipsrc */
      memcpy(&psk.psk_src.addr.v.a.addr, &target,
          sizeof(psk.psk_src.addr.v.a.addr));
      memset(&psk.psk_src.addr.v.a.mask, 0xff,
          sizeof(psk.psk_src.addr.v.a.mask));
      if (ioctl(dev, DIOCKILLSTATES, &psk))
            syslog(LOG_ERR, "DIOCKILLSTATES failed (%m)");

      /* Kill all states to ipsrc */
      memset(&psk.psk_src, 0, sizeof(psk.psk_src));
      memcpy(&psk.psk_dst.addr.v.a.addr, &target,
          sizeof(psk.psk_dst.addr.v.a.addr));
      memset(&psk.psk_dst.addr.v.a.mask, 0xff,
          sizeof(psk.psk_dst.addr.v.a.mask));
      if (ioctl(dev, DIOCKILLSTATES, &psk))
            syslog(LOG_ERR, "DIOCKILLSTATES failed (%m)");
}

/* signal handler that makes us go away properly */
static void
need_death(int signo)
{
      want_death = 1;
}

/*
 * function that removes our stuff when we go away.
 */
#ifdef __FreeBSD__
static __dead2 void
#else
static __dead void
#endif
do_death(int active)
{
      int   ret = 0;

      if (active) {
            change_filter(0, luser, ipsrc);
            change_table(0, ipsrc);
            authpf_kill_states();
            remove_stale_rulesets();
      }
      if (pidfile[0] && (pidfp != NULL))
            if (unlink(pidfile) == -1)
                  syslog(LOG_ERR, "cannot unlink %s (%m)", pidfile);
      exit(ret);
}

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